Fosi Audio P4 Preamplifier Review

[GianDi]

@JSmith took the interior photo in this review ;they suggest a better psu
you can see great performances of well-implemented ne5532. hope @Tofffsy won't beginning op-amp rolling

 

[morillon]

maybe an "se" version to come with a balanced output in addition....
(see to keep the volume and the appearance in "jack")
;-)
preamp> output impedance?

 

[GianDi]

IMHO instead of chasing balanced connections or separate components, Fosi should focus on creating a high-quality, fully integrated device—one that could shake up the entire market, outclassing the Wiim and all those overpriced pseudo-hi-end streamers.

Imagine an all-in-one unit that combines a streamer, DAC, preamp, and power amp, while also offering analog and phono inputs—and most importantly, featuring an internal power supply!

If you think about it, Fosi already has all the building blocks in its catalog:

• An excellent phono preamp
• A variety of DACs with coaxial, optical, USB, and Bluetooth inputs
• A solid analog input stage
• High-quality power amps in class-d and class ab

they need a good streamer module. I hope they will work hard,
I don’t currently own any Fosi devices because I’m not a fan of separate boxes, but I would definitely buy a well-engineered, great-sounding integrated amplifier from them.

 

[morillon]

IMHO instead of chasing balanced connections or separate components, Fosi should focus on creating a high-quality, fully integrated device—one that could shake up the entire market, outclassing the Wiim and all those overpriced pseudo-hi-end streamers.

Imagine an all-in-one unit that combines a streamer, DAC, preamp, and power amp, while also offering analog and phono inputs—and most importantly, featuring an internal power supply!

If you think about it, Fosi already has all the building blocks in its catalog:

• An excellent phono preamp
• A variety of DACs with coaxial, optical, USB, and Bluetooth inputs
• A solid analog input stage
• High-quality power amps in class-d and class ab

they need a good streamer module. I hope they will work hard,
I don’t currently own any Fosi devices because I’m not a fan of separate boxes, but I would definitely buy a well-engineered, great-sounding integrated amplifier from them.

The added value of Wiim is the streamer part... hardware and software... linkplay..

fosi doesn't seem to me to be in this area... and neither Wiim nor fosi seem to be oriented towards HDG...
affordable general public which is very respectable

 

[Waxx]

It's not my prefered format (i like rackwide devices with build in psu), but that is the only remark i can have on this. Noise and distortion is very low for such a cheap device, and the build quality looks more than decent. Functional you could wish for some kind of vu meter or level indicator, but that is not a nesecity, more like a nice option. But all these remarks are nitpicking. It's a great device, especially for it's price.

 

[morillon]

The egocentric "they must, it is necessary, I want, the most important thing..." that permeates all discussions concerning all these very mainstream brands, like wiim fosi etc is always astonishing... """"cheap of course!! or even cheaper!""

 

[Billy Budapest]

Excellent for what it is but the lack of triggers out and subwoofer out are too limiting .

Thanks for the review Amir.

There are two outputs (the RCA’s marked “output” and the mini jack marked “pre out”) so one of them could be used with a subwoofer. You would use the subwoofer’s internal crossover as it would be fed a full range signal.

 

[Bleib]

Hopefully not too long until they release a balanced version

 

[andymcbain]

I’m a big fan of these useful, low cost devices so it’s great to see this one performs well.

If this company made a low cost studio monitor controller in the same vein as something like the Drawmer CMC series, they’d probably sell a tonne of them.

 

[uwotm8]

Seems nice vol control for active speakers if one doesn't want to use DAC with volume control

 

[Mart68]

What is left to McIntosh, accuphase and all the other esoteric brands that sells for thousands and thousands...

Better looks, better build quality, long term satisfaction of use and ownership, possibly / probably greater reliability?

Appreciate it's a lot more to spend just to get those things.

I voted this 'Fine' - I'll vote 'Great' when they start making them look like proper hi-fi kit. Even if that doubles the price it's still very cheap.

 

[uwotm8]

What is left to McIntosh, accuphase and all the other esoteric brands that sells for thousands and thousands...

Implying actual Fosi audience includes McIntosh buyers (or the opposite, works both ways)

Anyway, it will mostly compete with classic passive volume knob "preamps" in desktop setups and the latter have price advantage.

 

[Heinrich]

A too limited feature set, I think. It would boil down to volume control, which is done w/ a potentiometer, yet motorized, but I would need at least 4 channels (beyond stereo) with better precision. For activated speakers, subs, external e/q. The tone controls won‘t help, if you look up various speakers or different room acoustics.

 

[Tofffsy]

@JSmith took the interior photo in this review ;they suggest a better psu
you can see great performances of well-implemented ne5532. hope @Tofffsy won't beginning op-amp rolling

After several active I own a passive Khozmo preamp and I'm more than happy with it, I don't understand why to add something active between my sources and my amps as this one is the first that doesn't downgrade the signal here. But as I already own several different opamps I would certainly give them a try if I would not have already sold them.

 

[morillon]

on this type of machine...without balance...

it lacks an essential measurement, even more important than "-1db sinad at 1khz better" etc...
the balance between L/R channels as the potentiometer travels...
this is the weakness of the essential machines with this type of modest potentiometers...
where attenuators with calibrated resistances or digital approaches take a clear advantage, unfortunately necessarily a little expensive...

 

[Sokel]

on this type of machine...without balance...

it lacks an essential measurement, even more important than "-1db sinad at 1khz better" etc...
the balance between L/R channels as the potentiometer travels...
this is the weakness of the essential machines with this type of modest potentiometers...
where attenuators with calibrated resistances or digital approaches take a clear advantage, unfortunately necessarily a little expensive...

Yep,the meaningful measurement of a pre is the range and quality of attenuation, it's rare that the travel will go to the 3'o'clock point (if it's done right) so it will start amplifying.
Amir measured it at 1'o'clock, that's about unity gain ballpark.

A -40 to -20dB is the absolute must,that's were it will be most of the time.
The agreement of channels seems ok at the charts with the input signal but the SINAD chart already shows some minor difference between them and unfortunately this difference usually tends to grow when attenuating if the pot is not of a good quality (=expensive, there's no way around this) .

 

[Tatteredmidnight]

on this type of machine...without balance...

it lacks an essential measurement, even more important than "-1db sinad at 1khz better" etc...
the balance between L/R channels as the potentiometer travels...
this is the weakness of the essential machines with this type of modest potentiometers...
where attenuators with calibrated resistances or digital approaches take a clear advantage, unfortunately necessarily a little expensive...

Beat me to it, I think the standard channel balance test would be one of the most important things to have here.

 

[morillon]

Yep,the meaningful measurement of a pre is the range and quality of attenuation, it's rare that the travel will go to the 3'o'clock point (if it's done right) so it will start amplifying.
Amir measured it at 1'o'clock, that's about unity gain ballpark.

A -40 to -20dB is the absolute must,that's were it will be most of the time.
The agreement of channels seems ok at the charts with the input signal but the SINAD chart already shows some minor difference between them and unfortunately this difference usually tends to grow when attenuating if the pot is not of a good quality (=expensive, there's no way around this) .

video ocilloscope -capture l/r , with the potentiometer's movement, is generally instructive....

 

[Music1969]

But no channel imbalance measurement?

 

[Hipster Doofus]

I spent $55 to replace my wiper blades yesterday… I know I could have done better…but maybe Fosi could do wiper blades next….with optional power supply of course to keep cost down.